From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on yquem.inria.fr X-Spam-Level: * X-Spam-Status: No, score=1.8 required=5.0 tests=AWL,DNS_FROM_RFC_POST, SPF_NEUTRAL autolearn=disabled version=3.1.3 X-Original-To: caml-list@yquem.inria.fr Delivered-To: caml-list@yquem.inria.fr Received: from mail4-relais-sop.national.inria.fr (mail4-relais-sop.national.inria.fr [192.134.164.105]) by yquem.inria.fr (Postfix) with ESMTP id 757D8BBAF for ; Wed, 11 Mar 2009 15:20:39 +0100 (CET) X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AswBAOllt0nRVd2Cm2dsb2JhbACCfpFyPwEBAQEBCAkKCRGqV4EGj3IBAwEDhAoG X-IronPort-AV: E=Sophos;i="4.38,343,1233529200"; d="scan'208";a="36405439" Received: from mail-qy0-f130.google.com ([209.85.221.130]) by mail4-smtp-sop.national.inria.fr with ESMTP; 11 Mar 2009 15:20:38 +0100 Received: by qyk36 with SMTP id 36so39215qyk.1 for ; Wed, 11 Mar 2009 07:20:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:in-reply-to:references :date:message-id:subject:from:to:cc:content-type :content-transfer-encoding; bh=wibifqZbIMg30cZHTgbYeFiP701RWDjYJodmUgcgFq8=; b=W640PZ12CtTZBv0TDHWbrD04B2kAJctt0JiQQ2fUZ8vxuYiW2ctS0RqlOQUigPZDcx 0rWF9CMUTw2r8PijLsf4hhxbHdj9SPFddXlNBzlMtpv7KFVKB60EyZ1p6My4oVBRe50E /XSyJDRDfrwIexB1F9bmOso5z2mkvTcgztyME= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=P4qNTgH8JooWBwWFam6HmjbwYgVGCYVgl8lw8rvALSNDTcHhyxbhkVKbhk1U5ekoN1 ZPTxuvPEFkslVsYs1hiu5zgAL5BHXx9awwwFS2+YhjOHvA6LhiCvoTuW2Z8qQlxS4pR2 fmjH5BQ+C/uX/YM8nv7MYdLpA2uSWc3kkbNXI= MIME-Version: 1.0 Received: by 10.220.46.146 with SMTP id j18mr3126873vcf.45.1236781237791; Wed, 11 Mar 2009 07:20:37 -0700 (PDT) In-Reply-To: <21952156.346634.1236751878001.JavaMail.www@wwinf1b03> References: <87prgoydy1.fsf@aryx.cs.uiuc.edu> <21952156.346634.1236751878001.JavaMail.www@wwinf1b03> Date: Wed, 11 Mar 2009 10:20:37 -0400 Message-ID: Subject: Re: [Caml-list] typing problem with sexplib and mutually recursive polymorphic types From: Markus Mottl To: yoann padioleau Cc: Caml-list List Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Spam: no; 0.00; recursive:01 markus:01 mottl:01 markus:01 mottl:01 recursive:01 recursion:01 undecidable:01 ocaml:01 2009:98 polymorphic:01 polymorphic:01 wrote:01 typing:01 caml-list:01 On Wed, Mar 11, 2009 at 02:11, yoann padioleau wrote: > Yes on this example, but what if I can't move it out because > the types really need to be mutually recursive ? I'm afraid, I don't see any straightforward way of achieving this goal. If the above were allowed in a truly recursive way, you'd essentially end up with polymorphic recursion, which is undecidable. Regards, Markus -- Markus Mottl http://www.ocaml.info markus.mottl@gmail.com